1. Field of Invention
The present invention is directed to the field of metal forging and, more particularly, to an apparatus for use in a forging press to near net warm forge relatively complex shaped parts from axi-symmetrical workpieces, and also to a forging method utilizing the apparatus to produce such parts from such workpieces.
2. Description of Related Art
Near net warm forging apparatuses and processes have been employed to produce relatively simple parts. Near net warm forging is a term which defines that the workpieces or billets have substantially the same volume as the finished parts. Present near net warn forging apparatuses and processes can only be used when the workpieces are snugly received within the die cavity. Such apparatuses and processes utilize workpiece material efficiently because the produced parts have at most only a small amount of excess material (flash). This flash can be removed by relatively simple secondary operations, to produce the finished parts. Near net forging apparatuses and processes can generally reduce processing costs by efficient material utilization, and by simplifying and reducing the number of secondary operations.
Known near net warm forging apparatuses and processes are not capable, however, of producing satisfactory parts having certain complex configurations and/or of producing satisfactory parts when the workpieces are not snugly received within the die cavity. For example, a particular part configuration that cannot be satisfactorily produced by known near net warm forging apparatuses and methods is a configuration that includes at least one protrusion that is significantly laterally offset from the longitudinal central axis of the finished part. This part configuration may be curved in one or more planes and stepped in other planes transverse to the planes in which the part is curved. The protrusion may lie in the same plane as that in which the part is curved, and may be centrally located along the longitudinal central axis.
The reason that known warm forging apparatuses and methods can not form this and other complex part configurations is that material of the workpieces does not sufficiently move or flow into all areas of the die cavity during the forging cycle. This is particularly true of areas of the configurations that are significantly laterally spaced from the central axis of the cavity.
The movement or flow of workpiece material in a forging process depends in part on the location of the workpieces within the female die, and so it is important that the workpieces are properly located in the die cavity. The known near net warm forging apparatuses and methods do not properly locate the workpiece within the die cavity unless, as stated, the workpieces fit snugly within the die cavity.
Accordingly the problems that need to be overcome to produce certain complex parts by near net warm forging are the proper flow of workpiece material within the die cavity and properly locating the workpieces within the die cavity. As stated, known near net warm forging apparatuses and methods can not move a sufficient amount of material of the workpieces into all of the areas of a die cavity which define certain complex configurations, and also do not properly locate the workpieces along both the length and the width of the die cavity, to form properly filled parts. This results in non-functional parts that must be scrapped or recycled.
Attempts have been made to overcome the problem of underfilling areas of the die cavity for such part configurations by using "overpacked" workpieces having a greater volume than that of the finished parts. Although all areas of the die cavity may be sufficiently filled by this approach, the forged parts are overpacked and include a significant volume of excess material (flash), particularly at regions opposite to the die cavity areas which are the farthest from the workpiece, i.e., which require that the workpiece material flow the farthest to be filled. This excess material must be removed by a secondary machining operation, such as grinding, to produce finished parts having the desired shape and volume for their intended purpose. Thus, overpacking the workpieces is not a satisfactory solution because it results in an inefficient utilization of material and also increases the difficulty and cost of producing the parts. The secondary operation to remove the excess material from the parts not only increases the number of process steps, but also is subject to human error and undesirably produces scrap parts.
Thus, there is a need for a forging apparatus that can be used to near net warm forge axi-symmetrical workpieces to form parts having certain relatively complex configurations, and also for a method of near net warm forging such parts utilizing the apparatus, that overcome the above-described problems of underfilling and overpacking. Certain aspects of this invention meet this need, along with other needs which will be apparent to those skilled in the art upon review of this disclosure.